Apparatus for forming metal-paper laminate electrostatically



May 9, 1967 F. UNGERER ET AL APPARATUS FOR FORMING METAL-PAPER LAMINATEELECTROSTATICALLY 5 'Sheets-Sheet 1 QI'iginaI Filed March 14, 1961 INVENTOR May 9, 1967 F. UNGERER ET AL 3,318,751 APPARATUSFOR FORMINGMETAL'PAPER LAMINATE ELECTROSTATICALLY Original Filed March 14 1961 5Sheets-Sheet 2 May 9, 1967 FUNGERER ET AL 3,

APPARATUS FOR FORMING METAL*PAPE3R LAMINATE SW' M Ww Q M1 United StatesPatent ()fice Claims. 61. 156-380) This is a division of applicationSer. No. 95,629, filed Mar. 14, 1961, now abandoned.

This invention relates'to a process and apparatus for adhesivelyconnecting a paper strip to a continuous metal strip, particularly abrass strip, which paper strip is intended as an interlayer between themetal plates to be stacked after they have been cut from said metalstrip.

When metal strips, particularly brass strips, pass through flying shearsfor being cut to metal plates, paper strips are supplied as a covering,to serve as an interlayer between stacked sheet metal plates after thecutting operation and to protect the surface of the plates. During thecutting and stacking of the sheet metal plates, this covering of thinpaper tends to be displaced owing to air movements and the like so thata perfect protection of the sheet metal surface is not achieved. The useof adhesives for connection at localized points is not feasible becausethis would adversely affect the bright sheet metal plates, particularlybrass plates.

The process and apparatus according to the invention afford a solutionto this problem. The process according to the invention for adhesivelyconnecting a paper strip to a continuous metal strip, which paper stripis to serve as an interlayer between the metal plates to be stackedafter being cut, is characterized in that electric charges forestablishing electric fields between the paper and metal strips areapplied to the paper strip which is superimposed on the metal strip andtogether with it is fed to the cutting shears, whereby electric fieldsare established between the paper and metal strips to retain the paperstrip for a short time until these charges have been automaticallydissipated on the metal strip. As a result, the paper strip firmlyadheres to the metal strip or the metal plates during the cut and afterthe cut during stacking whereas the electric fields dissipated withinshort time, i.e., in about four to five minutes, so that the adhesiveforce disappears too. Since the cutting and stacking operation performedafter the electric charging takes only a few seconds, the time of fourto five minutes during which the adhesive force is maintained isentirely sulficient to achieve the desired purpose and the thin coveringpaper can be readily removed for the subsequent further processing ofthe metal panels.

Transversely extending pointed electrode members may be disposed overthe metal strip fed to the cutting station and having the paper stripsuperimposed thereon. Having a high voltage applied to them thesepointed electrode members are adapted to transmit charges by a coronadischarge to establish the fields. Air ions are formed at the point ofthe electrode members which consist suitably of sewing needles arrangedone beside the other in a comblike arrangement in an open-bottomed,elongated housing of insulating material. These air ions move to thepaper under the action of the electrode field and pass through theslightly conducting paper layer and through the inter layer between thepaper and sheet metal. Owing to the unevenness of the materials, anextremely thin air gap exists between the paper layer and the sheetmetal backing.

3,3 18,75 1 Patented May 9, 1 967 The insulation value of this air gapis very high compared to that of the paper. The electric charge carriersare discharged only in very small amounts through this gap to the otherpole, formed by the metal backing. The paper surface which faces themetal backing and the surface of the latter form thus the plates of acapacitor, which attract with the force K=const. U /d (U=voltage at thecapaci tor and d=spacing of capacitor plates) per unit of area. When thesupply of new charge carriers is discontinued because the feeding of thestrips toward the shears is continued, the capacitor will be graduallydischarged because the interlayer is not an ideal insulator.

Brush rollers, e.g., of plastics, which rotate at a peripheral speedhigher than the speed of the strip and which contact the metal strip fedto the cutting station and having the paper strip superimposed thereon,may be provided to supply the charges for the generation of fields bymeans of friction. In the first case the corona discharge device issupplied with a rectified alternating current at a high voltage and alow current value, which alternating current.

is obtained from the alternating current supply system and transformedto a high voltage by means of a transformer. In the second case thecharge is applied by frictional electricity. The first method is simplerand more reliable than the second because the second process requires aspecial, high-speed drive for the friction brushes and the generatedfield and consequently the adhesive force does not have the sameintensity.

The drawing shows by way of example an embodiment of apparatus forcarrying out the process according to the invention. Specifically,

FIG. 1 is an elevation showing diagrammatically the corona dischargeapparatus according to the invention for a metal strip covered by apaper strip, which apparatus serves for causing the paper to adhere fora short time on the metal strip during and after the cutting of themetal to metal plates.

FIGS. 2 and 3 are diagrammatic fragmentary elevation and longitudinaland transverse sectional views show-.

ing the corona discharge device of FIG. 1.

FIG. 4 shows diagrammatically in elevation the circuit of the coronadischarge device of FIG. 1..

As is apparent in FIG. 1 of the drawing, the metal strip, e.g., a brassstrip 1, is withdrawn in known manner from a coil 2 and with the aid offeed rollers 3 is moved to the cutting shears 4, which cut the stripinto metal plates 5 of the desired size. Before the cut, a paper strip 6is fed to the metal strip 1 from a roll 7 with the aid of the rollers 3.The top roller may be rubber-coated to apply the paper strip 6 underslight pressure to the metal strip 1. The corona discharge device 8according to the invention is arranged behind this feeding device andconsists of pointed electrode members 9 which are spaced from each othertransversely to the metal strip and have a high voltage, e.g., of8,00010,000 volts applied to them while passing a low current, e.g.,0.001 ampere, to generate electric fields which cause the paper strip 6to adhere to the metal strip 1. This ensures a firm adherence for ashort time during the cutting to form metal plates 5 having a papercovering 10 and the subsequent stacking in the car 11. The electricfields have dissipated after about 4 to 5 minutes so that the paper 10can readily be removed during the further processing of the metal plates5. The cutting and stacking operations taking only a few seconds, thetime of adherence is entirely suificient for the desired adhesiveeffect.

As is apparent from FIGS. 2 and 3, the corona discharge device 8comprises an open-bottomed, elongated housing 12 of insulating material,which housing accommodates the pointed electrode members 9 in the formof sewing needles spaced one beside the other in a comblike arrangement.As is apparent from FIG. 4, the corona discharge device 8, 9 is fed fromthe supply systern 13 by means of the transformer 14 with high-voltagealternating current of about 8,00010,000 volts at a current value ofabout 0.001 ampere. This current is preferably rectified by means ofseries-connected rod-type rectifiers 15, which are connected by a highresistance 16 to the needle points 9.

According to a further concept of the invention the metal strip 1 fed tothe cutting station and the superimposed paper strip 6 may beelectrically charged by means of plastic brush rollers contacting thepaper strip and having a peripheral speed which is higher than the stripspeed. This is not particularly shown on the drawings. In such case,however, a special drive, having a higher speed, for the frictionbrushes is provided and the intensity of the field and the adhesiveforce are not so large as in the case described first.

In the drawings, the process as well as the apparatus according to theinvention are indicated only diagrammatically. The installationcomprises additional machines, such as a withdrawing device forwithdrawing the metal strip from the coil, a straightening machine,which succeeds the withdrawing device and straightens and feeds thestrip. A cleaning device may also be provided in dependence on theconditions of the individual case. The stacking device disposed behindthe fiying shears intended for continuous operation is also indicatedonly diagrammatically because various machines may be used for thispurpose and several machines may also follow here. The invention ensuresthat the paper adheres to the surface of the metal strip during thecutting operation and when the metal plates have been cut off and duringthe fall in the stacking machine so that the surface of the plates isprotected and cannot be scratched during their further handling. Thepaper coverings can then be removed without difficulty for thesubsequent further processing.

I claim:

1. Apparatus for temporarily securing a pair of superimposed elongatedstrips at least one of which is electrostatically chargeable and thematerial of said strips exhibiting the tendency of temporarily adheringto each other when said one strip is electrostatically charged,comprising, in combination, feeding means for continuously feeding saidpair of superimposed elongated strips along a predetermined path;electrostatic means adjacent said predetermined path for applying tosaid one strip an electrostatic charge whereby said strips adhere toeach other; severing means located along said path close to anddownstream of said electrostatic means for severing the adheringsuperimposed strips into individual laminated plates of correspondingadhering strip sections; and stacking means located close to anddownstream of said severing means for stacking said plates fed from saidsevering means while the electrostatic charge persists and the stripsections constituting each of said plates continue to adhere to eachother.

2. An apparatus according to claim 1, wherein said electrostatic meansincludes a plurality of electrodes extending at right angles to saidstrips and spaced from each other transversely of said strips, each ofsaid electrodes having a pointed free end spaced from said strips, andmeans for applying a high voltage to said electrodes to cause electriccharges to be applied to said one strip by a corona discharge, saidplates being adapted to be stacked face to face on said transfer meanswith the sections of said one strip alternating in stacked position withthe sections of the other.

3. An apparatus as set forth in claim 2 wherein said means for applyinga high voltage to said electrodes comprises a circuit connected to saidelectrodes and including a rectifier and a transformer, said transformerbeing adapted to be connected to an alternating current supply and todeliver a high voltage, alternating current of low current value to saidrectifier, which latter is adapted to transform said current intorectified current prior to feeding the same to said electrodes.

4. An apparatus as set forth in claim 2, wherein said electrodes areneedle-like and are arranged in a comblike manner, said apparatusfurther comprising an openbottomed housing of insulating materialcontaining said needle-like electrodes.

5. An apparatus according to claim 1, wherein said electrostatic meanscomprises thereon, brush roller means contacting said paper strip, andmeans for driving said brush roller means at a peripheral speed which ishigher than the feeding speed of said strips.

References Cited by the Examiner UNITED STATES PATENTS 2,388,069 10/1945Meaker et a1 156510 2,881,470 4/ 1959 Berthold et a1 a- 156-2722,923,964 2/1960 Plonsky 156-272 3,054,708 9/1962 Steinberg 156-2723,106,502 10/1963 Starger et a1. 156-272 EARL M. BERGERT, PrimaryExaminer.

DOUGLAS 1. DRUMMOND, Examiner.

1. APPARATUS FOR TEMPORARILY SECURING A PAIR OF SUPERIMPOSED ELONGATEDSTRIPS AT LEAST ONE OF WHICH IS ELECTROSTATICALLY CHARGEABLE AND THEMATERIAL OF SAID STRIPS EXHIBITING THE TENDENCY OF TEMPORARILY ADHERINGTO EACH OTHER WHEN SAID ONE STRIP IS ELECTROSTATICALLY CHARGED,COMPRIING, IN COMBINATION, FEEDING MEANS FOR CONTINUOUSLY FEEDING SAIDPAIR OF SUPERIMPOSED ELONGATED STRIPS ALONG A PREDETERMINED PATH;ELECTROSTATIC MEANS ADJACENT SAID PREDETERMINED PATH FOR APPLYING TOSAID ONE STRIP AN ELECTROSTATIC CHARGE WHEREBY SAID STRIPS ADHERE TOEACH OTHER; SEVERING MEANS LOCATED ALONG SAID PATH CLOSE TO ANDDOWNSTREAM OF SAID ELECTROSTATIC MEANS FOR SEVERING THE ADHERINGSUPERIMPOSED STRIPS INTO INDIVIDUAL LAMINATED PLATES OF CORRESPONDINGADHERING STRIP SECTIONS; AND STACKING MEANS LOCATED CLOSE TO ANDDOWNSTREAM OF SAID SEVERING MEANS FOR STACKING SAID PLATES FED FROM SAIDSEVERING MEANS WHILE THE ELECTROSTATIC CHARGE PERSISTS AND THE STRIPSECTIONS CONSTITUTING EACH OF SAID PLATES CONTINUE TO ADHERE TO EACHOTHER.